1. Field of the Invention
The present invention relates to soundproof walls. More precisely, the present invention relates to soundproof walls having multiple layer construction using basalt insulation.
2. Prior Art and Related Information
Sound absorption is fairly important in today's noisy society. In an environment that is growing in population density, noise pollution is a common problem. For example, sound transmission in a densely populated apartment complex, a busy freeway where traffic noise is high, or even a busy office with constant telephone rings or typewriter din exemplify environments where soundproofing and noise reduction are important.
Noise reduction technology is also important in certain acoustical environments such as in a concert hall, movie theater, or restaurant. It is desirable to have precise control of the acoustics so that patrons can fully enjoy their aural experience.
There have been various attempts at reducing noise and controlling sound. As seen in many movie theaters, sound engineers often cover all hard, reflective surfaces with cloth curtains, carpeting or other sound absorbent material. Moreover, by shaping the surface of the walls, it is possible to cause sound waves at given frequencies to cancel out thereby minimizing noise. This technology is well-known in the art.
There are several patents directed to a soundproof wall. For example, U.S. Pat. No. 4,838,524 to McKeown, et al., discloses a sound-proof wall comprising of a front corrugated, perforated sheet and a rear corrugated solid sheet which together define a chamber, with a central sinusoidally corrugate perforated sheet within the chamber. A blanket of noise-absorbing material is disposed over each side of the central sinusoidally corrugated perforated sheet.
U.S. Pat. No. 5,246,760 to Krickl discloses an insulating material for walls, ceilings, and roofs consisting of a sheep wool fleece sandwiched between two layers of needled non-woven material. Krickl also relies on mineral wool to be placed in the walls, ceilings, and roofs of buildings.
U.S. Pat. No. 4,923,034 to Okuzawa et al. discloses a vibration controlling member for use in a floor board and the like in a multi-stored apartment house or condominium. Okuzawa discloses multi-layered sheets having top and bottom plates sandwiching a foamed body sheet for shock absorption. The foam body sheet is formed by a polymeric material and includes, internally, a flake-shaped powdery substance. The top surface plate is formed from a wooden material or a polymeric material such as a synthetic resin; the bottom plate is formed from similar type material.
U.S. Pat. No. 4,842,097 to Woodward et al. discloses a sound-absorbing structure for a wall or ceiling having acoustic cavities behind the panels and slots in the panels for air flow. Some cavities are devoid of any insulation materials, and other cavities enclose at least some insulation material.
U.S. Pat. No. 4,607,466 to Allred discloses an acoustic panel having a porous layer and a generally rigid layer affixed to each other. The rigid layer includes at least one passage way opening on one side of the ridged layer and extends through the rigid layer through the porous layer. The passage way opening has dimensions set according to the Helmholtz resonance theory so that the panel vibrates thereby absorbing sound waves.
U.S. Pat. No. 4,487,291 to Walker discloses sound attenuation partitions for a building having a cavity between opposing panels which are enhanced by a bowed blanket of mineral fibers within the cavity.
There have been other attempts at noise absorption not necessarily relating to building construction. For example, U.S. Pat. No. 5,268,540 to Rex discloses a sound-absorbing noise barrier panel made from reinforced, pre-cast concrete panel skin formed with structural ribs extending therefrom at spaced intervals to provide structural strength to the panel and to form compartments throughout the panel. The compartments are filled with sound-absorbing materials and covered with a protective metal mesh which is, in turn, covered with decorative material which allows penetration of noise. There is also a second outer cover of fiberglass reinforced concrete lattice.
U.S. Pat. No. 5, 153,388 to Wittenmayer et al. describes a sound insulating arrangement for partition walls in motor vehicles. The sound insulating arrangement comprises a thin foam layer facing the sheet metal or other surface element, a heavy layer and an airborne sound absorber laminated or foamed thereon.
U.S. Pat. No. 5,187,996 to Alts describes a sound absorbing multi-layer structure made of a structural part that is capable of oscillating and a loosely-engaging damping sheet which sheet comprises a flexible material and high material absorption factor, and is made up of a heavy sheet with a visco-elastic support layer tightly connected thereto.
U.S. Pat. No. 4,130,175 to Hehmann discloses an acoustic suppression panel made from a perforated plate covering a layer of fibrous bulk absorber. A flexible, fluid-impervious membrane is placed between the perforated plate and the bulk absorber and is separated from the bulk absorber by spacers that permit the membrane to become essentially, acoustically transparent and to move or vibrate. The acoustic suppression panel is designed for use in an aircraft engine environment.
In view of the foregoing, there is a need for a multi-layered sound insulating barrier exploiting the benefits of a layer of basalt insulation.